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Microplásticos no rio Tejo em Portugal
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Nos ultimos anos, é crescente o número de investigações e pesquisas sobre os microplásticos
em diversos países, devido ao significativo impacte gerado ao meio ambiente, a
biota e a saúde humana. Em Portugal não é diferente, contudo, os estudos são geralmente
limitados quanto à abrangência e predominantemente em zona costeira (mar, praias e estuários),
sendo limitados os estudos em águas interiores.
Esta dissertação, num trabalho pioneiro, buscou identificar e avaliar a presença de microplásticos
no rio Tejo em Portugal, desde as praias junto à foz, passando pelo estuário até
a fronteira com a Espanha. Para tal foram realizadas recolhas de amostras de sedimentos em
30 pontos e de água superficial em 05 (cinco) pontos, totalizando 35 pontos de amostragem.
As recolhas foram realizadas em dezembro de 2020. Durante as análises laboratoriais, foram
encontrados microplásticos em todos os pontos de amostragem, cujas concentrações médias
foram de 0,54±0,5 Mp/m3 nas amostras de água, e nas amostras de sedimentos de 10,9±4,7
Mp/kg.
Dentre os municípios analisados, Almada apresentou as maiores concentrações de MP
nas amostras de água, com 1,3 Mp/m3, enquanto Vila Velha de Rodão apresentou as menores
concentrações, com 0,2 Mp/m3. No caso das amostras de sedimento, o município de Almeirim
apresentou as maiores concentrações com 20,1 Mp/kg, enquanto que o município de
Seixal apresentou as menores concentrações, com 2,71 Mp/kg.
Quanto à composição dos microplásticos encontrados no rio Tejo, os tamanhos predominantes
foram entre 0,1 e 0,5 mm, e as cores verdes, transparente (incolor), branco e azul
foram mais presentes. Nas amostras de água, a tipologia de microplástico mais abundante
foi o filme, seguido dos fragmentos, enquanto que nas amostras de sedimento, a tipologia
mais abundante foi de filamento seguido dos fragmentos. Quanto à composição dos polímeros,
houve o predomínio de Polietileno de baixa densidade - PEBD (30,6%), Polipropileno -
PP (27,9%), Polietileno de alta densidade - PEAD (22,8%) e Poliestireno expandido (4,7%).
De acordo com os resultados obtidos foi possível comprovar que as variaveis independetes
de distância da linha de costa, grau de urbanização, acessibilidade ao serviço de
recolha, taxa de reciclagem de recolha seletiva e população, interferem diretamente nas concentrações
de microplásticos no rio Tejo.
In recent years, there has been an increasing number of investigations and research on micro-plastics in several countries, due to the significant impact generated on the environment, biota and human health. In Portugal it is no different, however, studies are generally limited in scope and predominantly in coastal areas (sea, beaches and estuaries), with studies in inland waters being limited. This dissertation, in a pioneering work, sought to identify and evaluate the presence of microplastics in the Tagus River in Portugal, from the beaches near the mouth, through the estuary to the border with Spain. For this purpose, sediment samples were collected at 30 points and surface water samples at 05 (five) points, totaling 35 sampling points. The collections were carried out in December 2020. During the laboratory analyses, microplastic were found at all sampling points, whose average concentrations were 0.54±0.5 Mp/m3 in the water samples, and in the sediment samples of 10.9±4.7 Mp/kg. Among the analyzed municipalities, Almada had the highest concentrations of microplastic in the water samples, with 1.3 Mp/m3, while Vila Velha de Rodão had the lowest concentrations, with 0.2 Mp/m3. In the case of sediment samples, the municipality of Almeirim presented the highest concentrations with 20.1 Mp/kg, while the municipality of Seixal presented the lowest concentrations, with 2.71 Mp/kg. As for the composition of the microplastic found in the Tagus River, the predominant sizes were between 0.1 and 0.5 mm, and the colors green, transparent (colorless), white and blue were more present. In water samples, the most abundant microplastic typology was film, followed by fragments, while in sediment samples, the most abundant typology was filament followed by fragments. As for the composition of the polymers, there was a predominance of Low Density Polyethylene - LDPE (30.6%), Polypropylene - PP (27.9%), High Density Polyethylene - HDPE (22.8%) and Expanded Polystyrene (4 .7%). According to the results obtained, it was possible to prove that the independent variables of distance from the coastline, degree of urbanization, accessibility to the collection service, recycling rate of selective collection and population, directly interfere with PM concentrations in the Tagus River.
In recent years, there has been an increasing number of investigations and research on micro-plastics in several countries, due to the significant impact generated on the environment, biota and human health. In Portugal it is no different, however, studies are generally limited in scope and predominantly in coastal areas (sea, beaches and estuaries), with studies in inland waters being limited. This dissertation, in a pioneering work, sought to identify and evaluate the presence of microplastics in the Tagus River in Portugal, from the beaches near the mouth, through the estuary to the border with Spain. For this purpose, sediment samples were collected at 30 points and surface water samples at 05 (five) points, totaling 35 sampling points. The collections were carried out in December 2020. During the laboratory analyses, microplastic were found at all sampling points, whose average concentrations were 0.54±0.5 Mp/m3 in the water samples, and in the sediment samples of 10.9±4.7 Mp/kg. Among the analyzed municipalities, Almada had the highest concentrations of microplastic in the water samples, with 1.3 Mp/m3, while Vila Velha de Rodão had the lowest concentrations, with 0.2 Mp/m3. In the case of sediment samples, the municipality of Almeirim presented the highest concentrations with 20.1 Mp/kg, while the municipality of Seixal presented the lowest concentrations, with 2.71 Mp/kg. As for the composition of the microplastic found in the Tagus River, the predominant sizes were between 0.1 and 0.5 mm, and the colors green, transparent (colorless), white and blue were more present. In water samples, the most abundant microplastic typology was film, followed by fragments, while in sediment samples, the most abundant typology was filament followed by fragments. As for the composition of the polymers, there was a predominance of Low Density Polyethylene - LDPE (30.6%), Polypropylene - PP (27.9%), High Density Polyethylene - HDPE (22.8%) and Expanded Polystyrene (4 .7%). According to the results obtained, it was possible to prove that the independent variables of distance from the coastline, degree of urbanization, accessibility to the collection service, recycling rate of selective collection and population, directly interfere with PM concentrations in the Tagus River.
Descrição
Palavras-chave
Microplástico Poluição da Água Sedimento Rio Tejo Portugal