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- Compositional variation of soils from Cabo Mondego (Portugal): new data to support environmental studiesPublication . Heck Michels, Fernando; Ribeiro, Joana; Henriques, Maria Helena; Misz-Kennan, Magdalena; Fabiańska, MonikaABSTRACT: This study aims to determine physicochemical parameters of soils from Cabo Mondego area (Central Portugal), allowing the establishment of the natural background to serve as a reference to identify variations resulting from industrial activities. Forty-three surface soil samples were collected near the deactivated industrial complex and another seven in more distant areas. The soils present a predominantly sandy texture and pH values in the alkaline range, which reflects the geological signature. The soils electrical conductivity of five samples present values above the Portuguese reference value for contaminated soils. The anomalous values measured in a sample (CM-S3) were related to the presence of coal mining wastes located nearby. From the determined elements, the most abundant is Ca reflecting the limestone rocks composition, and a lithological control was identified in the spatial analysis, where higher concentrations of Fe and Al are coincident to the spatial occurrence of carbonaceous complex and limestones.
- Natural radioactivity of soils surrounding the deactivated Sines thermal power plant: impacts of coal combustionPublication . Erbolato Filho, José; Ribeiro, Joana; Pereira, AlcidesABSTRACT: For 36 years, the coal combustion in Sines thermal power plant generated a complex mixture of gases and particles that were partially emitted into the atmosphere and the environment. The determination of radiological parameters in soils surrounding the power plant reveals that soils in the southern area have higher activity concentration of natural radionuclides (40K, 232Th, and 238U), as well as higher exhalation rates and emanation coefficients of 222Rn and 220Rn than those located at north. The higher values of radiological parameters in the southern area are explained by dispersion of gases and particles driven by the preferential direction of winds and the proximity to storage facilitates of coal and products derived from combustion. The higher exhalation rates and low emanation coefficients of thoron indicates that K and Th may be accumulated and encapsulated in the mineral fraction of ash particles while U, preferentially bounded to organic matter, was mobilized during coal combustion. The results do not indicate a significant radiological risk, although it is higher in the southern area.
- Aplicação do método de resistividade elétrica na caracterização do calcário em exploração numa pedreira de rocha ornamentalPublication . Gomes, Alexandre; Duarte, João; Ribeiro, JoanaRESUMO: O principal objetivo deste trabalho foi a caracterização do maciço calcário explorado na pedreira “EM&R nº 6478”, com base na aplicação do método geofísico de resistividade elétrica, tendo em vista a otimização da operação extrativa de calcário para fins ornamentais. Pretende-se identificar as zonas do maciço com coloração acinzentada, que apresentam menor interesse económico. Verificou-se que os valores de resistividade elétrica sofrem variações significativas nas zonas de contato entre as zonas de coloração bege e as zonas de coloração acinzentada do calcário. Constatou-se que a tonalidade acinzentada se deve à presença de uma fração argilosa na sua composição, que pode explicar os valores mais baixos de resistividade elétrica. A metodologia utilizada revelou-se bastante eficaz no planeamento futuro da exploração, permitindo uma melhor orientação das frentes de desmonte, tornando a exploração ainda mais rentável.